The effectiveness of nitroimidazoles against trichomonads has been known since the discovery of the antibiotic azomycin (2-nitroimidazole, S. Nakamura and H. Umezawa, J. Antibiotics (Tokyo), 9 A, 66 [ 1955]). However, this compound and other 2-nitroimidazoles proved to be no more effective in vitro than metronidazole (5-nitro-2-methyl-1-(2-hydroxyethyl)-imidazole), G. C. Lancini, E. Lazzari, R. Pallanea, 11 Farmaco Ed Sc. 21, 278 [ 1966]) and the ED.sub.50 - and LD.sub.50 -values were considerably less favorable (E. Grunberg. F. Titsworth, Antimicrobial Agents and Chemotherapy, 1965, 1966, 478). Only from the 5-nitroimidazoles evolved the best among a large number of synthesized compounds, viz., the commercial preparation metronidazole (C. Cosar, "Arzneimittelforschung", 16, 23 [ 1966]). See also French Pat. No. 1,212,028 which has a minimum inhibitory concentration of 2.5 g/ml. against Trichomonas vaginalis.
It has now been discovered that the known 1-substituted 5-nitro-2-imidazolyl-iminocarboxylic acid esters can be removed with ammonia or ammonium salts to produce novel 1-substituted 5-nitro-2-imidazolyl-carboxamidines, which also have trichomonicidal activity, which compounds can then be reacted with .beta.-dicarboxy compounds and or the derivatives thereof to produce 2-(5-nitro-2-imidazolyl)-pyrimidines, which are more effective than metronidazole in trichomonacidal activity.